1. Field of the Invention
This invention relates to microwave chokes for power supplies in electronic amplifiers, signal generators, and filters.
2. Description of Prior Art
Microwave chokes are used to block microwave energy from power supplies in amplifiers, signal generators, and filters. Laser drivers for fiber optic cables also require chokes between their power sources and the lasers. Broadband active filters require broadband chokes. If microwave energy leaks into a power supply, the powered device will not function properly. Microwave chokes typically operate within a narrow band of operating frequencies. However, the fiber optic cables now used in cable television and internet communication typically have extremely large band widths and require amplifiers which will amplify signals for all of the frequencies being transmitted over these cables.
In order to cover the broad spectrum of frequencies, multiple narrow band amplifiers are usually employed, each covering a small segment of the frequency range. These amplifiers are operated in parallel. All of the devices used in these amplifiers would generally function over the entire frequency range except for the chokes. If a broadband choke were available, a single broadband amplifier could replace several narrow-band amplifiers.
Until recently, the highest frequency broadband chokes available would only operate up to 3 or 4 GHz. These chokes generally had a conventional geometry such as a solenoid or a toroid, and used an air, iron, or ferrite core. Beyond this frequency range, multiple small solenoids were typically used, but these devices have a narrow frequency range of about 10% of the center frequency of operation.
Prior leadless carriers for broadband chokes used a ceramic substrate with wraparound connections. However, such a carrier design introduces the dielectric properties of the carrier into the performance of the choke. Additionally the prior carriers have metallic pads for connection of the leads, and these pads add substantial capacitance and dielectric losses. This prior carrier design is marginally useable up to 8 Ghz with the new inductor described herein. However, high frequency performance requires a different approach to the leadless carrier.